package com.yangmy.cobweb.common.core.utils;

/**
 * @author YangMingYang
 * @since 2022/7/29
 */

import org.springframework.util.ObjectUtils;

import java.net.*;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.Optional;

/**
 * 获取本机IP 地址
 *
 * @author dingwen
 * 2021.04.28 11:49
 */
public class IpUtils {
    /*
     * 获取本机所有网卡信息   得到所有IP信息
     * @return Inet4Address>
     */
    public static List<Inet4Address> getLocalIp4AddressFromNetworkInterface() throws SocketException {
        List<Inet4Address> addresses = new ArrayList<>(1);

        // 所有网络接口信息
        Enumeration<NetworkInterface> networkInterfaces = NetworkInterface.getNetworkInterfaces();
        if (ObjectUtils.isEmpty(networkInterfaces)) {
            return addresses;
        }
        while (networkInterfaces.hasMoreElements()) {
            NetworkInterface networkInterface = networkInterfaces.nextElement();
            //滤回环网卡、点对点网卡、非活动网卡、虚拟网卡并要求网卡名字是eth或ens开头
            if (!isValidInterface(networkInterface)) {
                continue;
            }

            // 所有网络接口的IP地址信息
            Enumeration<InetAddress> inetAddresses = networkInterface.getInetAddresses();
            while (inetAddresses.hasMoreElements()) {
                InetAddress inetAddress = inetAddresses.nextElement();
                // 判断是否是IPv4，并且内网地址并过滤回环地址.
                if (isValidAddress(inetAddress)) {
                    addresses.add((Inet4Address) inetAddress);
                }
            }
        }
        return addresses;
    }

    /**
     * 过滤回环网卡、点对点网卡、非活动网卡、虚拟网卡并要求网卡名字是eth或ens开头
     *
     * @param ni 网卡
     * @return 如果满足要求则true，否则false
     */
    private static boolean isValidInterface(NetworkInterface ni) throws SocketException {
        return !ni.isLoopback() && !ni.isPointToPoint() && ni.isUp() && !ni.isVirtual()
                && (ni.getName().startsWith("eth") || ni.getName().startsWith("ens"));
    }

    /**
     * 判断是否是IPv4，并且内网地址并过滤回环地址.
     */
    private static boolean isValidAddress(InetAddress address) {
        return address instanceof Inet4Address && address.isSiteLocalAddress() && !address.isLoopbackAddress();
    }

    /*
     * 通过Socket 唯一确定一个IP
     * 当有多个网卡的时候，使用这种方式一般都可以得到想要的IP。甚至不要求外网地址8.8.8.8是可连通的
     * @return Inet4Address>
     */
    private static Optional<Inet4Address> getIpBySocket() throws SocketException {
        try (final DatagramSocket socket = new DatagramSocket()) {
            socket.connect(InetAddress.getByName("8.8.8.8"), 10002);
            if (socket.getLocalAddress() instanceof Inet4Address) {
                return Optional.of((Inet4Address) socket.getLocalAddress());
            }
        } catch (UnknownHostException networkInterfaces) {
            throw new RuntimeException(networkInterfaces);
        }
        return Optional.empty();
    }

    /*
     * 获取本地IPv4地址
     * @return Inet4Address>
     */
//    public static Optional<Inet4Address> getLocalIp4Address() throws SocketException {
//        final List<Inet4Address> inet4Addresses = getLocalIp4AddressFromNetworkInterface();
//        if (inet4Addresses.size() != 1) {
//            final Optional<Inet4Address> ipBySocketOpt = getIpBySocket();
//            if (ipBySocketOpt.isPresent()) {
//                return ipBySocketOpt;
//            } else {
//                return inet4Addresses.isEmpty() ? Optional.empty() : Optional.of(inet4Addresses.get(0));
//            }
//        }
//        return Optional.of(inet4Addresses.get(0));
//    }

    public static String getLocalIp4Address() {
        if(ip==null){
            try {
                final List<Inet4Address> inet4Addresses = getLocalIp4AddressFromNetworkInterface();
                if (inet4Addresses.size() != 1) {
                    final Optional<Inet4Address> ipBySocketOpt = getIpBySocket();
                    ip = ipBySocketOpt.map(Inet4Address::getHostAddress).orElseGet(() -> inet4Addresses.isEmpty() ? null : Optional.of(inet4Addresses.get(0)).get().getHostAddress());
                }
                ip= Optional.of(inet4Addresses.get(0)).get().getHostAddress();
            } catch (SocketException ignored) {}
        }
        return ip;
    }

    private static String ip = null;

}

